The Brumbies have knocked out defending Super Rugby champions the Chiefs after clinging on for a 32-30 win in an epic qualifying final in Canberra.

The Brumbies raced out to a 22-3 lead on Saturday night, but as they learnt in last year's grand final, you can never write off a side chasing their third straight title. All Blacks fly-half Aaron Cruden spearheaded the fightback as the Chiefs levelled the scores midway through the second half.

But the Brumbies regained the advantage with a converted try from a well-constructed driving maul before Cruden failed to convert a Gareth Anscombe five-pointer with three minutes to go. It was sweet revenge for the Brumbies as Ben Mowen won what is likely to be his last and 50th game as skipper in front of 14,284 fans at Canberra's GIO Stadium.

A fourth-minute yellow card to Chiefs centre Tim Nanai-Williams for cynical ruck play hurt the visitors, the Brumbies crossing twice in his absence and then immediately after his return to race out to a 19-3 lead.

Wallabies scrum-half Nic White was brilliant, scoring the first of his side's four tries from a surprise snipe and delivering crisp ball all night. Workhorse lock Sam Carter was brilliant in getting over the advantage line, while it took three Chiefs players to bring down superb winger Henry Speight on most occasions.

Fullback Jessie Mogg brilliantly attacked from a kick return in the ninth minute to put over Robbie Coleman, giving the Brumbies a 14-3 lead. The Chiefs dug in until Nanai-Williams came back on, but the defence would soon again crack, Mogg finishing off an 18-phase attack to go up 19-3 in just the 20th minute. Christian Leali'ifano then knocked over a penalty but the Chiefs would finish the half on a high with Bundee Aki scoring to narrow the gap to 22-10.

Both sides traded penalties after the break, before the game was turned on its head, dangerman Speight binned in the 49th minute for the same reason as Nanai-Williams was in the first half.

Chiefs halfback Tawera Kerr-Barlow then scored to make it a five-point game before Nanai-Williams crossed to level the scores. Leali'ifano then missed a simple penalty shot, but they soon made amends when Jarrad Butler crashed over from the back of a rolling maul that involved several backline players. But the Chiefs weren't done, Anscombe scoring his side's fourth try before Cruden crucially missed the conversion from the corner.

Brumbies captain Ben Mowen was pleased with his side's performance but also paid tribute to the Chiefs for their dominance in recent years.

"We knew it was going to have to be a full 80 [minute] performance," he told Fox Sports. "You just don't knock a side like that over easily. We're very proud of that effort and you've got to give a lot of credit to the Chiefs for what they've done in the last three years - it's been outstanding effort from them to be there.

"Both sides were going to go hard at the breakdown and push those [refereeing] decisions and I thought Craig [Juoubert] handled that really well and made clear decisions.

Mowen said the Brumbies tactics of playing atttacking rugby from the outset had paid dividends

"We've been working hard on our skill - not just in the past two weeks, but probably the past two months - and getting good transfer out of the game. It's exciting to play and when you keep getting results like that you've got to keep backing it."

Chiefs skipper Aaron Cruden was obviously disappointed with the result but praised his side's determined second-half fightback.

"It wasn't the result we were after. We started pretty slowly and gave a quality side like the Brumbies a lead like that and we did really well to peg it back and showed a lot of character, but in these play-off games you need to be clinical for 80 minutes.

"We created a lot of chances and the momentum kept swinging between the sides. We had the Brumbies down in their 22 and were attacking well but they seemed to have the desire on their line and worked well for each other."